Reorganize webpack configuration structure

Author: TheLarkInn

packages/react-dev-utils/README.md

@@ -412,5 +412,5 @@ Returns a cache identifier (string) consisting of the specified environment and
 ```js
 var getCacheIdentifier = require('react-dev-utils/getCacheIdentifier');
 
-getCacheIdentifier('prod', ['react-dev-utils', 'chalk']); // # => 'prod:[email protected]:[email protected]'
+getCacheIdentifier('production', ['react-dev-utils', 'chalk']); // # => 'prod:[email protected]:[email protected]'
 ```